A subsurface micro irrigation system marketed and manufactured by Aquapore Moisture Systems of Phoenix, Arizona is designed for applying the precise amount of water directly to the plant root zone. The objective of the micro irrigation system is to constantly supply each plant with sufficient soil moisture to meet its evapotranspiration demands.
A typical subsurface micro irrigation system can include a main water supply line connected to a source of water and a plurality of feed lines of porous irrigation pipe extending from the main water supply line. The feed lines are buried several inches beneath the surface of the ground to deliver water directly to the plant root zones. The terminal ends of the feed lines are connected to flush ports either directly or via flush lines. Flow regulators are coupled between the main line and feed lines to ensure a constant downstream flow of water regardless of pressure variations upstream for applying the precise amount of water to the plant root zones by the feed lines. Pressure gauges are installed downstream of the flow regulators to monitor water pressure in the flow lines.
An ideal soil moisture is thus maintained by means of water delivered at controlled constant rates through the feed lines of porous irrigation pipe. In response to low water pressure, the pores in the walls of the pipe pass water from the pipe and out into the soil. By capillary action, the water then moves through the soil to the plant roots. Also, chemical nutrients and fertilizers can be injected into the feed lines and fed to the plant root zones through the pipe wall pores for optimization of the root zone environment.
The micro's irrigation system preferably employs a porous pipe that emits water throughout its surface when placed under pressure. A preferred porous pipe is described in U.S. Pat. No. 4,517,316. This type of porous pipe contains a dispersion of elastoner particles such as ground rubber reclaimed from tires in a thermoplastic binder such as polyethylene. Apparently the polyethylene does not bind well to the rubber granules forming channels from the inside of the pipe to the outer wall. The porous pipe appears to weep water when placed under pressure.
From time to time, minerals from hard water and other debris can accumulate and deposit in the pores of the porous pipe walls and begin to clog the feed lines. This condition can be detected by noting an increase in water pressure at the pressure gauges since the flow regulators in the feed lines function to emit the same amount of water, even as the pipe wall pores begin to clog, but just at a higher pressure. In order to unclog the pores of the pipe walls, the water pressure can be substantially increased to expand the pipe walls and their pores and thereby dislodge the trapped minerals and debris. Pore clearing or cleaning is enhanced by material such as detergents.
One prior art approach to increasing water pressure for the purpose of unclogging the porous pipe is to provide a branch assembly in each feed line composed of pipe elbows, tees and short sections for connecting a by-pass valve in parallel with each flow regulator and to allow injection of cleaning material. The by-pass valve is opened temporarily whenever unclogging has to be undertaken. A significant shortcoming of this prior art approach is the added time and expense of installing and maintaining the components of these branch assemblies. As a consequence, there is a need for improvement of this prior art approach to reduce or eliminate this shortcoming.